LXR linux/include/linux/key.h

   1/* Authentication token and access key management
   2 *
   3 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 *
  11 *
  12 * See Documentation/security/keys.txt for information on keys/keyrings.
  13 */
  14
  15#ifndef _LINUX_KEY_H
  16#define _LINUX_KEY_H
  17
  18#include <linux/types.h>
  19#include <linux/list.h>
  20#include <linux/rbtree.h>
  21#include <linux/rcupdate.h>
  22#include <linux/sysctl.h>
  23#include <linux/rwsem.h>
  24#include <linux/atomic.h>
  25#include <linux/assoc_array.h>
  26
  27#ifdef __KERNEL__
  28#include <linux/uidgid.h>
  29
  30/* key handle serial number */
  31typedef int32_t key_serial_t;
  32
  33/* key handle permissions mask */
  34typedef uint32_t key_perm_t;
  35
  36struct key;
  37
  38#ifdef CONFIG_KEYS
  39
  40#undef KEY_DEBUGGING
  41
  42#define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  43#define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  44#define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  45#define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  46#define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  47#define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  48#define KEY_POS_ALL     0x3f000000
  49
  50#define KEY_USR_VIEW    0x00010000      /* user permissions... */
  51#define KEY_USR_READ    0x00020000
  52#define KEY_USR_WRITE   0x00040000
  53#define KEY_USR_SEARCH  0x00080000
  54#define KEY_USR_LINK    0x00100000
  55#define KEY_USR_SETATTR 0x00200000
  56#define KEY_USR_ALL     0x003f0000
  57
  58#define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  59#define KEY_GRP_READ    0x00000200
  60#define KEY_GRP_WRITE   0x00000400
  61#define KEY_GRP_SEARCH  0x00000800
  62#define KEY_GRP_LINK    0x00001000
  63#define KEY_GRP_SETATTR 0x00002000
  64#define KEY_GRP_ALL     0x00003f00
  65
  66#define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  67#define KEY_OTH_READ    0x00000002
  68#define KEY_OTH_WRITE   0x00000004
  69#define KEY_OTH_SEARCH  0x00000008
  70#define KEY_OTH_LINK    0x00000010
  71#define KEY_OTH_SETATTR 0x00000020
  72#define KEY_OTH_ALL     0x0000003f
  73
  74#define KEY_PERM_UNDEF  0xffffffff
  75
  76struct seq_file;
  77struct user_struct;
  78struct signal_struct;
  79struct cred;
  80
  81struct key_type;
  82struct key_owner;
  83struct keyring_list;
  84struct keyring_name;
  85
  86struct keyring_index_key {
  87        struct key_type         *type;
  88        const char              *description;
  89        size_t                  desc_len;
  90};
  91
  92/*****************************************************************************/
  93/*
  94 * key reference with possession attribute handling
  95 *
  96 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  97 * defined. This is because we abuse the bottom bit of the reference to carry a
  98 * flag to indicate whether the calling process possesses that key in one of
  99 * its keyrings.
 100 *
 101 * the key_ref_t has been made a separate type so that the compiler can reject
 102 * attempts to dereference it without proper conversion.
 103 *
 104 * the three functions are used to assemble and disassemble references
 105 */
 106typedef struct __key_reference_with_attributes *key_ref_t;
 107
 108static inline key_ref_t make_key_ref(const struct key *key,
 109                                     bool possession)
 110{
 111        return (key_ref_t) ((unsigned long) key | possession);
 112}
 113
 114static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 115{
 116        return (struct key *) ((unsigned long) key_ref & ~1UL);
 117}
 118
 119static inline bool is_key_possessed(const key_ref_t key_ref)
 120{
 121        return (unsigned long) key_ref & 1UL;
 122}
 123
 124/*****************************************************************************/
 125/*
 126 * authentication token / access credential / keyring
 127 * - types of key include:
 128 *   - keyrings
 129 *   - disk encryption IDs
 130 *   - Kerberos TGTs and tickets
 131 */
 132struct key {
 133        atomic_t                usage;          /* number of references */
 134        key_serial_t            serial;         /* key serial number */
 135        union {
 136                struct list_head graveyard_link;
 137                struct rb_node  serial_node;
 138        };
 139        struct rw_semaphore     sem;            /* change vs change sem */
 140        struct key_user         *user;          /* owner of this key */
 141        void                    *security;      /* security data for this key */
 142        union {
 143                time_t          expiry;         /* time at which key expires (or 0) */
 144                time_t          revoked_at;     /* time at which key was revoked */
 145        };
 146        time_t                  last_used_at;   /* last time used for LRU keyring discard */
 147        kuid_t                  uid;
 148        kgid_t                  gid;
 149        key_perm_t              perm;           /* access permissions */
 150        unsigned short          quotalen;       /* length added to quota */
 151        unsigned short          datalen;        /* payload data length
 152                                                 * - may not match RCU dereferenced payload
 153                                                 * - payload should contain own length
 154                                                 */
 155
 156#ifdef KEY_DEBUGGING
 157        unsigned                magic;
 158#define KEY_DEBUG_MAGIC         0x18273645u
 159#define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 160#endif
 161
 162        unsigned long           flags;          /* status flags (change with bitops) */
 163#define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 164#define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 165#define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 166#define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 167#define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 168#define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 169#define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 170#define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 171#define KEY_FLAG_TRUSTED        8       /* set if key is trusted */
 172#define KEY_FLAG_TRUSTED_ONLY   9       /* set if keyring only accepts links to trusted keys */
 173
 174        /* the key type and key description string
 175         * - the desc is used to match a key against search criteria
 176         * - it should be a printable string
 177         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 178         */
 179        union {
 180                struct keyring_index_key index_key;
 181                struct {
 182                        struct key_type *type;          /* type of key */
 183                        char            *description;
 184                };
 185        };
 186
 187        /* type specific data
 188         * - this is used by the keyring type to index the name
 189         */
 190        union {
 191                struct list_head        link;
 192                unsigned long           x[2];
 193                void                    *p[2];
 194                int                     reject_error;
 195        } type_data;
 196
 197        /* key data
 198         * - this is used to hold the data actually used in cryptography or
 199         *   whatever
 200         */
 201        union {
 202                union {
 203                        unsigned long           value;
 204                        void __rcu              *rcudata;
 205                        void                    *data;
 206                        void                    *data2[2];
 207                } payload;
 208                struct assoc_array keys;
 209        };
 210};
 211
 212extern struct key *key_alloc(struct key_type *type,
 213                             const char *desc,
 214                             kuid_t uid, kgid_t gid,
 215                             const struct cred *cred,
 216                             key_perm_t perm,
 217                             unsigned long flags);
 218
 219
 220#define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 221#define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 222#define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 223#define KEY_ALLOC_TRUSTED       0x0004  /* Key should be flagged as trusted */
 224
 225extern void key_revoke(struct key *key);
 226extern void key_invalidate(struct key *key);
 227extern void key_put(struct key *key);
 228
 229static inline struct key *__key_get(struct key *key)
 230{
 231        atomic_inc(&key->usage);
 232        return key;
 233}
 234
 235static inline struct key *key_get(struct key *key)
 236{
 237        return key ? __key_get(key) : key;
 238}
 239
 240static inline void key_ref_put(key_ref_t key_ref)
 241{
 242        key_put(key_ref_to_ptr(key_ref));
 243}
 244
 245extern struct key *request_key(struct key_type *type,
 246                               const char *description,
 247                               const char *callout_info);
 248
 249extern struct key *request_key_with_auxdata(struct key_type *type,
 250                                            const char *description,
 251                                            const void *callout_info,
 252                                            size_t callout_len,
 253                                            void *aux);
 254
 255extern struct key *request_key_async(struct key_type *type,
 256                                     const char *description,
 257                                     const void *callout_info,
 258                                     size_t callout_len);
 259
 260extern struct key *request_key_async_with_auxdata(struct key_type *type,
 261                                                  const char *description,
 262                                                  const void *callout_info,
 263                                                  size_t callout_len,
 264                                                  void *aux);
 265
 266extern int wait_for_key_construction(struct key *key, bool intr);
 267
 268extern int key_validate(const struct key *key);
 269
 270extern key_ref_t key_create_or_update(key_ref_t keyring,
 271                                      const char *type,
 272                                      const char *description,
 273                                      const void *payload,
 274                                      size_t plen,
 275                                      key_perm_t perm,
 276                                      unsigned long flags);
 277
 278extern int key_update(key_ref_t key,
 279                      const void *payload,
 280                      size_t plen);
 281
 282extern int key_link(struct key *keyring,
 283                    struct key *key);
 284
 285extern int key_unlink(struct key *keyring,
 286                      struct key *key);
 287
 288extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 289                                 const struct cred *cred,
 290                                 key_perm_t perm,
 291                                 unsigned long flags,
 292                                 struct key *dest);
 293
 294extern int keyring_clear(struct key *keyring);
 295
 296extern key_ref_t keyring_search(key_ref_t keyring,
 297                                struct key_type *type,
 298                                const char *description);
 299
 300extern int keyring_add_key(struct key *keyring,
 301                           struct key *key);
 302
 303extern struct key *key_lookup(key_serial_t id);
 304
 305static inline key_serial_t key_serial(const struct key *key)
 306{
 307        return key ? key->serial : 0;
 308}
 309
 310extern void key_set_timeout(struct key *, unsigned);
 311
 312/**
 313 * key_is_instantiated - Determine if a key has been positively instantiated
 314 * @key: The key to check.
 315 *
 316 * Return true if the specified key has been positively instantiated, false
 317 * otherwise.
 318 */
 319static inline bool key_is_instantiated(const struct key *key)
 320{
 321        return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 322                !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 323}
 324
 325#define rcu_dereference_key(KEY)                                        \
 326        (rcu_dereference_protected((KEY)->payload.rcudata,              \
 327                                   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 328
 329#define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 330do {                                                                    \
 331        rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD));          \
 332} while (0)
 333
 334#ifdef CONFIG_SYSCTL
 335extern ctl_table key_sysctls[];
 336#endif
 337/*
 338 * the userspace interface
 339 */
 340extern int install_thread_keyring_to_cred(struct cred *cred);
 341extern void key_fsuid_changed(struct task_struct *tsk);
 342extern void key_fsgid_changed(struct task_struct *tsk);
 343extern void key_init(void);
 344
 345#else /* CONFIG_KEYS */
 346
 347#define key_validate(k)                 0
 348#define key_serial(k)                   0
 349#define key_get(k)                      ({ NULL; })
 350#define key_revoke(k)                   do { } while(0)
 351#define key_invalidate(k)               do { } while(0)
 352#define key_put(k)                      do { } while(0)
 353#define key_ref_put(k)                  do { } while(0)
 354#define make_key_ref(k, p)              NULL
 355#define key_ref_to_ptr(k)               NULL
 356#define is_key_possessed(k)             0
 357#define key_fsuid_changed(t)            do { } while(0)
 358#define key_fsgid_changed(t)            do { } while(0)
 359#define key_init()                      do { } while(0)
 360
 361#endif /* CONFIG_KEYS */
 362#endif /* __KERNEL__ */
 363#endif /* _LINUX_KEY_H */
 364